The present invention relates to on-board computer networks in a motor vehicle, and to displaying information regarding operation of the motor vehicle.
Computer systems are incorporated into motor vehicles, such as long haul semi-trailer trucks for engine control, transmission operation, logging driver data and truck maintenance information and occupant comfort systems for example. The various computers are connected to a communication network that runs throughout the truck for the exchange of data and commands.
Some of the computers have dedicated control panels with input and display devices connected directly to the computer. In other cases, information about the truck""s performance is sent from the computers to a common display panel on the dashboard. That display panel typically includes a computer monitor screen and function selection switches. The information to be displayed has to be obtained by the display panel from the specific computer that controls the related vehicle function. This requires that the computers be programmed to transmit data messages periodically to the display panel, or that the display panel periodically requests the necessary data from those computers. In either situation, the vehicle computers have to be specifically programmed to communicate with the control panel.
Some trucks include a navigation system which utilizes signals from the Global Positioning System (GPS) to determine the present location of the truck and provided driving instructions to a desired destination. The navigation system typically incorporates a dedicated two dimensional display, similar to a computer screen, on which a map is displayed.
A truck also may have a collision avoidance system that senses the presence of other vehicles in close proximity in front of and behind the truck. This system also has dedicated display and warning devices. Because these types of sophisticated systems each has its own dedicated display it may be difficult to integrate those displays into the existing dashboard of a truck.
Although a significant amount of information is being exchanged among the truck""s computers, much of that information is not displayed to the driver. For example the actual pressure sensed for each of the tires may not be available for display, only a warning indication occurs when the pressure in a tire becomes to low. Individual drivers or trucking companies may desire that different ones of these other operational parameters be displayed. That requires custom reprogramming of the display panel and other computers in the vehicle. In addition, because dashboards typically have a integrated display devices, customizing a particular truck to display other operating parameters can necessitate creation of an entirely new dashboard layout, which is cost prohibitive for all but large volume truck purchasers.
In addition, a truck owner may desire to upgrade an older truck by adding a display panel, a navigation system or collision avoidance apparatus. However, this requires finding an area on the dashboard that is large enough to locate the driver interface components of such equipment. The existing computers in the truck also must be reprogrammed to send data messages to a newly added display panel. Thus adding after market equipment may be difficult to accomplish in a given truck.
A motor vehicle has numerous devices which exchange messages over a communication network. An indicator for the motor vehicle includes a circuit that is connected to the communication network and intercepts messages which are intended for receipt by a given device other than the indicator. The control circuit controls a display device to present information to the occupant of the motor vehicle in response to contents of the messages which are intercepted.
The operation of indicators, that eavesdrop on network messages, is defined by the protocol by which the messages are sent. In a common protocol, data is transmitted in a message packet that contains an address of the given device intended to receive the data, identification of an operating parameter of the motor vehicle, and a data value for that operating parameter. For this type of protocol, the control circuit intercepts message packets having a specific address. In other embodiments, the control circuit intercepts message packets having the identification of a predefined operating parameter.
Because this indicator uses data carried by messages already being sent between other devices on the network, network devices do not have to be programmed to send data specifically to the indicator. In fact, the indicator may not even require it own network address. This facilitates the addition of indicators to a vehicle as only the new indicator has to be configured to intercept messages carrying the data needed for the display of the information.